SUMMARY I am requesting an administrative supplement to my NIGMS grant (R37 GM058615) in order fund a micro-ultracentrifuge. We have been using a vesicle reconstitution system to elucidate the mechanistic details of vesicle formation from Golgi membrane. Recently, we have refined this approach, which has enabled us to gain even greater mechanistic insights into this process. Key to this refinement is the use of ultracentrifugation at greater than 100,000 x g force, so that 50nm-diameter vesicles can be distinguished from soluble proteins. So far, we have been going across campus to a lab that has a micro-ultracentrifuge for such small-volume analyses. However, this arrangement is becoming increasingly untenable, as it wastes much time, and more importantly, we cannot be always guaranteed access to the equipment when needed, as we are low-priority users. Thus, we are requesting funds to purchase of a micro-ultracentrifuge, specifically the Optima model offered by Beckman, because of its reliability and ease of use.